/**
 * libpsd - Photoshop file formats (*.psd) decode library
 * Copyright (C) 2004-2007 Graphest Software.
 *
 * libpsd is the legal property of its developers, whose names are too numerous
 * to list here.  Please refer to the COPYRIGHT file distributed with this
 * source distribution.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU Library General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU Library General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 * $Id: brightness_contrast.c, created by Patrick in 2006.05.22, libpsd@graphest.com Exp $
 */

#include <math.h>
#include "libpsd.h"
#include "psd_system.h"
#include "psd_stream.h"
#include "psd_rect.h"
#include "psd_math.h"


extern void psd_adjustment_blend_image(psd_context * context, psd_layer_record * layer, psd_rect * dst_rect,
    psd_uchar * lookup_table);


// Brightness and Contrast
psd_status psd_get_layer_brightness_contrast(psd_context * context, psd_layer_record * layer)
{
    psd_layer_brightness_contrast * data;
    
    layer->layer_info_type[layer->layer_info_count] = psd_layer_info_type_brightness_contrast;
    layer->layer_type = psd_layer_type_brightness_contrast;

    data = (psd_layer_brightness_contrast *)psd_malloc(sizeof(psd_layer_brightness_contrast));
    if(data == NULL)
        return psd_status_malloc_failed;
    memset(data, 0, sizeof(psd_layer_brightness_contrast));
    layer->layer_info_data[layer->layer_info_count] = (psd_uint)data;
    layer->layer_info_count ++;

    // Brightness
    data->brightness = psd_stream_get_short(context);
    // Contrast
    data->contrast = psd_stream_get_short(context);
    // Mean value for brightness and contrast
    data->mean_value = psd_stream_get_short(context);
    // Lab color only
    data->Lab_color = psd_stream_get_char(context);

    layer->adjustment_valid = psd_true;

    return psd_status_done;
}

psd_bool psd_layer_blend_brightness_contrast(psd_context * context, psd_layer_record * layer, psd_rect * dst_rect)
{
    psd_layer_brightness_contrast * data = NULL;
    psd_int i;
    psd_float brightness, contrast, slant, value;

    for(i = 0; i < layer->layer_info_count; i ++)
    {
        if(layer->layer_info_type[i] == psd_layer_info_type_brightness_contrast)
        {
            data = (psd_layer_brightness_contrast *)layer->layer_info_data[i];
            break;
        }
    }
    if(data == NULL)
        return psd_false;
    
    if(layer->adjustment_valid == psd_true)
    {
        if(data->brightness != 0 && data->contrast != 0)
        {
            brightness = (psd_float)data->brightness / data->mean_value;
            contrast = (psd_float)data->contrast / data->mean_value;
            slant = (psd_float)tan((contrast + 1) * PSD_PI_4);

            for(i = 0; i < 256; i ++)
            {
                value = i / 255.0f;
                if(brightness < 0.0)
                    value = value * (1.0f + brightness);
                else if(brightness > 0.0)
                    value = value + ((1.0f - value) * brightness);

                if(contrast != 0.0)
                    value = (value - 0.5f) * slant + 0.5f;
                value = 255 * value + 0.5f;
                value = PSD_CONSTRAIN(value, 0, 255);
                data->lookup_table[i] = (psd_int)value;
            }
        }
        else
        {
            for(i = 0; i < 256; i ++)
                data->lookup_table[i] = i;
        }
    }

    psd_adjustment_blend_image(context, layer, dst_rect, data->lookup_table);

    layer->adjustment_valid = psd_false;
    
    return psd_true;
}

